US4712751A - Tail end structure for an aircraft fuselage - Google Patents

Tail end structure for an aircraft fuselage Download PDF

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Publication number
US4712751A
US4712751A US06/886,792 US88679286A US4712751A US 4712751 A US4712751 A US 4712751A US 88679286 A US88679286 A US 88679286A US 4712751 A US4712751 A US 4712751A
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Prior art keywords
tail end
end structure
curvature
cross
section
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Expired - Lifetime
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US06/886,792
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English (en)
Inventor
Ernst H. Hirschel
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Airbus Defence and Space GmbH
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Messerschmitt Bolkow Blohm AG
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Assigned to MESSERSCHMITT-BOELKOW-BLOHM, GESELLSCHAFT MIT BESCHRAENKTER HAFTUNG, P.O. BOX 801109, 8000 MUENCHEN 80, GERMANY reassignment MESSERSCHMITT-BOELKOW-BLOHM, GESELLSCHAFT MIT BESCHRAENKTER HAFTUNG, P.O. BOX 801109, 8000 MUENCHEN 80, GERMANY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: HIRSCHEL, ERNST H.
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C1/00—Fuselages; Constructional features common to fuselages, wings, stabilising surfaces or the like
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C1/00—Fuselages; Constructional features common to fuselages, wings, stabilising surfaces or the like
    • B64C2001/0045—Fuselages characterised by special shapes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T50/00—Aeronautics or air transport
    • Y02T50/10—Drag reduction

Definitions

  • the invention relates to a tail end structure for the fuselage of an aircraft having a raised cross-sectional configuration deviating from a circular cross-section.
  • Tail end structures of this type are known, for example, from German Pat. No. 674,433 (Schroeder) and from U.S. Pat. No. 3,955,781 (Tupolev et al). It is also known to provide the tail end structure with a circular cross-section as, for example, in the well known airbus.
  • German Pat. No. 674,433 discloses a fuselage configuration having a somewhat oval upper cross-sectional configuration and a flattened lower cross-sectional configuration.
  • the fuselage itself is made of corrugated metal which is surrounded by a fabric or webbing secured to the ridges formed by the corrugations and covering the valleys between the ridges.
  • a particular tail end construction is not disclosed in German Pat. No. 674,433.
  • U.S. Pat. No. 3,955,781 discloses a delta winged aircraft with a fuselage having two portions. Each portion forms part of a circular cross-section, whereby the upper portion has a smaller radius and the lower portion has a substantially larger radius so as to flatten the bottom of the fuselage.
  • a specific tail end construction is not disclosed in Tupolev et al. There is room for improvement with regard to the tail end construction, especially with regard to providing better flow conditions for the air flow along the tail end structure.
  • tail end in such a way that drag is reduced as compared to the prior art, especially in comparison with tail end structures having circular cross-sections;
  • a tail end structure for the fuselage of an aircraft or spacecraft having cross-sections with a centroid displaced downwardly relative to the centroid of a circular cross-section.
  • This downward displacement of the cross-sectional centroid is achieved by downwardly and laterally extending lobes which are so sized that the lower, upper, and lateral boundary or silhouette contours remain unchanged within the silhouette of a tail end structure having a circular cross-section.
  • FIG. 1 is a schematic, symbolic illustration of the silhouette of an aircraft fuselage including the tail end structure located in a rectangular coordinate system, whereby the three sectional views are taken along section plane A--A, but through three different tail end structures to illustrate a conventional circular cross-section and two cross-sections through tail end structures according to the invention;
  • FIG. 2 is also a view against the section plane A--A, but on an enlarged scale as compared to FIG. 1, and illustrating in a superposed view the relationship between the circular conventional cross-sectional configuration (V0) and the modified cross-sectional configurations (V2, V3) according to the invention;
  • FIG. 2a shows the circular cross-sectional configuration (V0) of a conventional tail end structure providing a reference plane for defining the invention
  • FIG. 2b is a cross-sectional view of a tail end structure (V2) according to the invention.
  • FIG. 2c is another cross-sectional view of a tail end structure (V3) according to the invention.
  • FIG. 3 is a diagram showing the relationship of the curvature radii, of the centers of curvature spacings, of the circumference ratios, as well as the area ratios, all shown as a function of a tail end deformation factor ⁇ which is a dimensionless number ranging from zero, at the interface between the tail end structure and the fuselage, to one at the tail end;
  • FIG. 4 is a view from right to left in FIG. 1 against the tail end of the fuselage of the aircraft for showing the panel models for the right-hand half of the fuselage for a conventional tail end structure (V0) with a circular cross-section and for two embodiments (V2 and V3) of the invention;
  • FIG. 5a shows the frictionless flow lines and the boundary wall flow lines for a conventional tail end structure (V0);
  • FIGS. 5b and 5c are views similar to that of FIG. 5a, however, showing the frictionless flow lines and the boundary wall flow lines for the embodiments (V2 and V3) according to the invention;
  • FIG. 8a shows boundary layer separation configurations for a conventional tail section with a circular cross-section
  • FIG. 8b shows the boundary layer separation configurations of one embodiment (V3) of the tail section according to the invention illustrating the displacement of the separation bubble toward the tail end.
  • FIG. 1 illustrates symbolically an aircraft fuselage in a rectangular coordinate system wherein the ordinate is x3' and the abscissa is x1'. The ordinate and abscissa are indicated in meters.
  • the length of the front part and of the cylindrical part of the fuselage together is indicated by C2.
  • the circular cross-section V0 shown in FIG. 1 relates to a conventional tail end structure having this circular cross-section throughout its length Lref-C2.
  • the tail end structures of the invention V2 and V3 do not have such a circular cross-section.
  • the circular cross-section is used as a reference plane for comparing the cross-sections V2 and V3 according to the invention with the prior art V0.
  • FIG. 1 further shows a relative scale ⁇ ranging from zero to 1.
  • ⁇ is zero at the interface V--V where the tail section merges into the cylindrical part of the fuselage.
  • ⁇ is one at the very end of the tail structure.
  • the factor ⁇ represents the degree of deformation of the tail end structure according to the invention and is related to the x1' coordinate as follows:
  • the contour or silhouette boundaries for the conventional circular cross-section are provided by the top boundary line T, by the lateral boundary lines K3, and by the bottom boundary line U.
  • the silhouette or contour of the conventional circular cross-section is the same as viewed from all four directions.
  • the cross-sections V2 and V3 according to the invention deviate from the circular cross-section as shown, however, in such a way, that the tail end structures according to the invention remain within the contour or silhouette of the circular tail end structure V0. This is so even though the tail end structure V2 has lateral boundary lines K2 which are vertically aligned below the lateral boundary lines K3.
  • the circular cross-section of the conventional tail end structure V0 has a first centroid or surface center of gravity S1 located at the center of the circular cross-section having the radius ro.
  • the cross-sectional surfaces of the embodiments V2 and V3 have a second centroid S2 located below the first centroid S1 by a spacing a1 that will depend on the particular cross-sectional surface involved. Both centroids S1 and S2 are located on a central vertical line VL.
  • the cross-section V2 separately shown in FIG. 2b, according to the invention, has two laterally and downwardly extending first lobes W2 and an upwardly and centrally located lobe W2'.
  • the first lobes W2 are mirror-symmetrically arranged relative to the vertical line or plane VL. All the lobes W2 and W2' have the same radius r1 of curvature having a length as given below.
  • Each lobe W2 and W2' has a different center of curvature CC1, CC2, and CC3.
  • the centers of curvature CC1 and CC2 are located on their respective lobe line LL passing through the first centroid S1 and extending at an angle ⁇ of, for example, 45° relative to the vertical line VL.
  • the angle ⁇ is within the range of 35° to 55° preferably within the range of 40° to 50°.
  • the centers CC1 and CC2 are spaced from the first centroid S1 by a spacing a2.
  • the center of curvature CC3 for the upper central lobe W2' is located on the vertical line VL vertically above the first centroid S1 and spaced from the first centroid S1 by the above mentioned spacing a1.
  • the angular extent of the upper lobe W2' corresponds to 180°-2 ⁇ as shown, whereby ⁇ corresponds, for example, to 26.565°, however ⁇ may be within the range of 20° to 30°.
  • the angular extent of the two lower lobes W2 corresponds to 90°+ ⁇ as shown, whereby the 90° are measured between a vertical line extending through the respective center of curvature CC1 or CC2 in parallel to the central vertical line VL, and a horizontal line extending through both centers of curvature CC1 and CC2, as well as through the second centroid S2.
  • the angle ⁇ is measured against this horizontal line as shown.
  • the second embodiment V3 separately shown in FIG. 2c, according to the invention, has an upper portion forming a semi-circle coinciding with the upper part of the circular cross-section V0 of the prior art.
  • the lower portion of the cross-section V3 has two laterally and downwardly extending lobes W3 with a radius of curvature r3 having its origin in respective curvature centers CC4 and CC5 located on the above mentioned lobe lines LL and spaced from the first centroid S1 by the spacing a3.
  • the angular extent of the lobes W3 is approximately 90° as shown.
  • FIG. 3 shows the dimensional relationship of the above mentioned distances a1, a2, and a3 in meters as a function of the tail end deformation factor ⁇ .
  • FIG. 3 further shows the dimensional relationship of the above mentioned radii ro, r1, and r2 also as a function of the deformation factor in meters or fractions thereof.
  • FIG. 3 shows the surface ratios (F V2 /Fo) and (F V3 /Fo) and the circumferential ratios (U V2 /Uo) and (U V3 /Uo) of the cross-sections V2 and V3 according to the invention compared to the surface Fo and the circumference Uo of the conventional circular cross-section.
  • the respective conventional ratios are equal to one.
  • FIG. 3 illustrates the above relationships. It will also be seen from FIG. 3 that the surface area ratio (F V2 /Fo) and the circumferential ratio (U V2 /Uo) of the embodiment V2 according to the invention are quite close to one as mentioned above so that these ratios indicate that the embodiment V2 has substantially the same flow exposed surface area and substantially the same volume in the tail section as the conventional tail section V0. However, the different shape V2 improves the flow conditions.
  • the respective surface ratio (F V3 /Fo) and the circumferential ratio (U V3 /Uo) of the embodiment V3 shows that the volume and the flow exposed area are larger than in the conventional cross-section V0, and provides improved flow conditions.
  • FIG. 4 illustrates the so-called panel models for the conventional tail section V0.
  • Panel models for the tail sections V2 and V3 according to the invention are shown in the center and at right.
  • FIG. 5a shows by full lines the computed frictionless flow lines of the prior art tail end structure V0. Dashed lines show the boundary wall flow lines. These lines are drawn in the coordinate plane x ⁇ with the x1 and x2, whereby x ⁇ is a common reference plane. On the upper side the frictionless flow for the Vo structure is most divergent.
  • FIGS. 5b and 5c show the respective lines for a tail end structure V2 and V3 according to the invention respectively. It is noted that on the upper side of the embodiment V3 the least divergence takes place. The convergence on the other hand is the least on the lower side of the embodiment V2. However, for the boundary layer characteristic, a bend in the flow lines is controlling.
  • the left-hand part of each illustration shows the boundary layer thickness ⁇ while the right-hand part of each illustration shows the boundary layer displacement thickness ⁇ 1.
  • the boundary layer thickness increases toward the tail end on the underside of the fuselage, please see FIG. 6.
  • the thickening is less in the embodiments V2 and V3 of the invention.
  • a substantial thickening takes place while in the embodiments V2 and V3 of the invention merely a small lobe is formed in the boundary layer thickness contour adjacent to the lower plane of symmetry.
  • FIG. 6 shows that the boundary layer is thicker on the bottom of the tail end section of the fuselage than on its upper side.
  • the ratio of the boundary layer thickness to the boundary layer displacement thickness ( ⁇ / ⁇ 1) is in the same order of magnitude as the respective ratio of the two-dimensional reference plane also known as the 1/7--power-boundary layer.
  • the boundary layer thickness at the cross-section B--B (x1 0.89) as shown in FIG. 7, goes down from about 8.5 for V0 to about 2 for V2 and V3.
  • FIG. 8a shows in this respect the lobe formation of the thickness contour together with the convergence of the boundary wall flow lines providing the possibility of an embedded vortex type longitudinal separation to the left and right of the line of symmetry.
  • the separation bubble is shifted further down toward the end of a tail end section.
  • the boundary layer at the under surface of the structure V2 or V3 is not in danger of separation contrary to the prior art structure V0.
  • Locating the second centroid S2 below the conventional location at S1 by modifying the cross-sectional configuration to V2 or V3 results in a more advantageous boundary layer characteristic, especially at the lower surface of the tail end section in the embodiments V2 and V3 as compared to the conventional structure V0.
  • the structures V2 and V3 according to the invention are just as simple to manufacture as a tail section having a circular cross-section because the increase in the volume and surface do not pose any problems.
  • the separation characteristics and the drag characteristics are also impoved.
  • the wing and the raised tail end structure guide in the same manner the frictionless flow and thus the boundary layer under the tail end section. Further, the on-flow to the elevator assembly near the fuselage is improved.
  • Fo frame sectional surface of conventional tail section V0 having a circular cross-section.
  • F V2 ; F V3 frame sectional surface of tail sections V2 and V3 according to the invention.
  • U V2 ; U V3 circumference of tail sections V2 and V3 according to the invention.
  • K2 lateral contour boundary of embodiment V2.
  • T upper contour boundary line.
  • W2 lower lateral lobes (first lobes) of embodiment V2.
  • W2' upper central lobe (second lobe) of embodiment V2.
  • W3 lower lateral lobes (first lobes) of embodiment V3.
  • V0 cross-section through a conventional cylindrical tail structure providing a reference plane.
  • V2 cross-section through a first tail end structure according to the invention.
  • V3 cross-section through a second tail end structure according to the invention.
  • a1 spacing above first centroid S1 for defining center CC3 of curvature of a first lobe radius r2.
  • a2 spacing laterally below first centroid S1 for defining centers CC2, CC3 of curvature for first lobe radius r2.
  • a3 spacing laterally below first centroid S1 for defining centers CC4 and CC5 of curvature for second lobe radius r3.
  • Lref length of fuselage from nose tip to the end of the tail section.
  • C2 length of fuselage section including nose portion and cylindrical portion
  • C1+C2 Lref.
  • r1 first lobe radius of first tail cross-section V2 of invention, about 0.7 ⁇ ro.
  • x1 first surface coordinate for sectional plane.
  • x2 second surface coordinate for sectional plane.
  • x ⁇ reference plane for x1 or x2.
  • x1' rectangular reference coordinates.
  • x2' rectangular reference coordinates.
  • x3' rectangular reference coordinates, a dimensionless number.
  • ⁇ tail end coordinate
  • ⁇ boundary layer thickness
  • ⁇ 1 boundary layer displacement thickness
  • ⁇ lobe line angle, within range of about 35° to 55°.
  • ⁇ lobe limit angle, of about 26.565°.
  • S1 first surface center of gravity or centroid of circular sectional plane V0.
  • S2 second surface center of gravity or centroid of sectional planes through tail sections V2 and V3 of the invention.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Lining Or Joining Of Plastics Or The Like (AREA)
  • Casting Or Compression Moulding Of Plastics Or The Like (AREA)
  • Toys (AREA)
  • Main Body Construction Of Washing Machines And Laundry Dryers (AREA)
  • Lining And Supports For Tunnels (AREA)
  • Underground Or Underwater Handling Of Building Materials (AREA)
US06/886,792 1985-07-24 1986-07-16 Tail end structure for an aircraft fuselage Expired - Lifetime US4712751A (en)

Applications Claiming Priority (2)

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DE3526472 1985-07-24
DE19853526472 DE3526472A1 (de) 1985-07-24 1985-07-24 Rumpfheckmodifikation von flugzeugen

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JP (1) JPS6226200A (enExample)
DE (1) DE3526472A1 (enExample)
FR (1) FR2585326B3 (enExample)
GB (1) GB2177989A (enExample)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USD308663S (en) 1987-05-06 1990-06-19 The Boeing Company Airplane
US4953812A (en) * 1987-11-13 1990-09-04 The Boeing Company Aircraft configuration with aft mounted engines and method
US4976396A (en) * 1987-11-13 1990-12-11 The Boeing Company Aircraft configuration with aft mounted engines
US5677508A (en) * 1995-08-15 1997-10-14 Hughes Missile Systems Company Missile having non-cylindrical propulsion section
US5692704A (en) * 1995-06-07 1997-12-02 Buttgereit; Volker Body tail unit for a commercial aircraft
US5908175A (en) * 1997-11-19 1999-06-01 Magnes; Gene One-piece airplane tail-cone with inspection door(s)
US20120068014A1 (en) * 2010-09-16 2012-03-22 Airbus Operations Gmbh Segment of a fuselage of an aircraft
EP3064430A1 (en) * 2015-03-06 2016-09-07 Airbus Operations GmbH Extended rear pressure bulkhead
US20240124119A1 (en) * 2021-03-10 2024-04-18 Zsm Holdings Llc Aircraft fuselage configurations for upward deflection of art fuselage

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4404810C2 (de) * 1994-02-16 1999-12-09 Daimler Chrysler Aerospace Rumpfheck für ein Verkehrsflugzeug

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE674433C (de) * 1937-05-08 1939-04-14 Messerschmitt Boelkow Blohm An Luftfahrzeugen angeordnete, aus Wellblech bestehende Aussenbeplankung
FR1114301A (fr) * 1954-04-05 1956-04-11 Procédé économique de construction cellulaire
US3023860A (en) * 1957-03-18 1962-03-06 Floyd P Ellzey Body construction
US3955781A (en) * 1974-03-10 1976-05-11 Andrei Nikolaevich Tupolev Supersonic aircraft with the engines disposed under the delta wing middle portion

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE674433C (de) * 1937-05-08 1939-04-14 Messerschmitt Boelkow Blohm An Luftfahrzeugen angeordnete, aus Wellblech bestehende Aussenbeplankung
FR1114301A (fr) * 1954-04-05 1956-04-11 Procédé économique de construction cellulaire
US3023860A (en) * 1957-03-18 1962-03-06 Floyd P Ellzey Body construction
US3955781A (en) * 1974-03-10 1976-05-11 Andrei Nikolaevich Tupolev Supersonic aircraft with the engines disposed under the delta wing middle portion

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USD308663S (en) 1987-05-06 1990-06-19 The Boeing Company Airplane
US4953812A (en) * 1987-11-13 1990-09-04 The Boeing Company Aircraft configuration with aft mounted engines and method
US4976396A (en) * 1987-11-13 1990-12-11 The Boeing Company Aircraft configuration with aft mounted engines
US5692704A (en) * 1995-06-07 1997-12-02 Buttgereit; Volker Body tail unit for a commercial aircraft
US5677508A (en) * 1995-08-15 1997-10-14 Hughes Missile Systems Company Missile having non-cylindrical propulsion section
AU687686B2 (en) * 1995-08-15 1998-02-26 Raytheon Company Missile having non-cylindrical propulsion section
US5908175A (en) * 1997-11-19 1999-06-01 Magnes; Gene One-piece airplane tail-cone with inspection door(s)
US20120068014A1 (en) * 2010-09-16 2012-03-22 Airbus Operations Gmbh Segment of a fuselage of an aircraft
US8757545B2 (en) * 2010-09-16 2014-06-24 Airbus Operations Gmbh Segment of a fuselage of an aircraft
USD723447S1 (en) 2010-09-16 2015-03-03 Airbus Operations Gmbh Fuselage
EP3064430A1 (en) * 2015-03-06 2016-09-07 Airbus Operations GmbH Extended rear pressure bulkhead
US10689088B2 (en) 2015-03-06 2020-06-23 Airbus Operations Gmbh Extended rear pressure bulkhead
US20240124119A1 (en) * 2021-03-10 2024-04-18 Zsm Holdings Llc Aircraft fuselage configurations for upward deflection of art fuselage

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DE3526472A1 (de) 1987-02-05
JPS6226200A (ja) 1987-02-04
FR2585326A1 (fr) 1987-01-30
DE3526472C2 (enExample) 1987-05-07
FR2585326B3 (fr) 1987-10-16
GB8618031D0 (en) 1986-08-28
GB2177989A (en) 1987-02-04

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